Many automotive and other articles are molded or otherwise fabricated of thermoplastic compositions which embody about equal parts by weight of (1) an interpolymer of ethylene, one or more C.sub.3 -C.sub.16 mono-olefins, preferably propylene and a polyene, preferably 5-ethylidene-2-norbornene, generally referred to in the trade as an EPDM and (2) a thermoplastic polyolefin resin, preferably polypropylene. One of the problems faced by articles molded or otherwise fabricated of such TPO compositions, is the difficulty of achieving strong adherence of coatings applied to the surfaces of such articles, as in the color coating of such articles, especially with a polyurethane based coating composition.
To the present, in order to provide for a desirable adhesion of a paintable coating, it has been the practice to first apply an adhesion promoter, followed by the application of a prime coat, and then the application of the final paintable color coat. The ability to eliminate the promoter as a first coating while achieving strong adherence of the paintable color coating would materially enhance the entire process especially from the standpoint of material cost, processing time and conservation of space, equipment, and labor.